Fuel composition



FUEL COMPOSITION Jerome E. Brown and Hymin Shapiro, Detroit, Mich., assignors to Ethyl Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application March 28, 1956 Serial No. 574,386

7 Claims. (Cl. 44-74) This invention relates to improved hydrocarbon fuels for internal combustion engines.

Aromatic amines have been proposed as additives for hydrocarbon fuels as antiknock improvers. Aniline, for example, produces an antiknock efiect when included in a liquid hydrocarbon fuel of the gasoline boiling range. However, no widespread use has been made of aromatic amines as antiknock agents, as they have not been completely satisfactory in their effectiveness and because of their relatively low fuel solubility.

It is an object of this invention to provide a class of aromatic amines showing superior antiknock effectiveness.

Another object of this invention is to provide an improved hydrocarbon fuel for use in internal combustion engines. A further object of this invention is to provide a liquid hydrocarbon fuel containing suflicient amounts of certain aromatic amine compounds to materially enhance the antiknock qualities of the fuel.

The above and other objects. of this invention are accomplished by providing hydrocarbon fuels for spark ignition internal combustion engines which contain fluoro substituted aromatic amine compounds in amount sufiicient to improve the antiknock properties of the fuel.

The compounds of this invention which are suitable for use in liquid hydrocarbon fuels to give enhanced octane values comprise fluoro substituted amines of the general formula where R is hydrogen, alkyl, cycloalkyl, aryl, alkaryl or aralkyl; R is an alkyl group and n is or an integer from 1 to 4. When n is greater than one, R can represent the same or different alkyl groups. The groups represented by R and R in the above formula may be of any size or configuration. However, it is preferred that the aryl, alkaryl and aralkyl groups be limited to those containing at most carbon atoms; that the alkyl groups represented by R be limited to those containing from 1 to 4 carbon atoms and the alkyl groups represented by R be limited to those containing from 1 to 6 carbon atoms; as these compounds are more effective antiknock agents per unit weight.

Although ortho-, metaand para-fluoro substituted aromatic amines are suitable as additives in the practice of this invention, it has been found that the para-substituted compounds are the most efiective, and in particular it has been found, as will be pointed out in greater detail hereinafter, that parafiuoro aniline and N-methyl-p-fluoro aniline are superior antiknock agents. The most preferred embodiment of this invention comprises a liquid hydrocarbon fuel which contains small quantities of p-fluoro aniline, although this compound can be advantageously aren't Ice used in admixture with other fluoro substituted aromatic amines.

The fuels suitable in the practice of this invention include liquid hydrocarbon fuels of the gasoline boiling range and include, for example, pure hydrocarbons, mixtures of hydrocarbons and blends of gasoline derived from straight run or processed naturally occurring hydrocarbons.

In the practice of this invention the amount of fiuoro substituted aromatic amine employed per gallon of fuel varies depending on the enhancement in antiknock quality desired and the initial antiknock rating of the fuel employed. Thus, the amount can range from about 0.3 gram to about 250 grams of fluoro substituted amines per gallon of fuel. Concentrations of fiuoro substituted amines in excess of 250 grams per gallon can also be used, however because of the extreme antiknock effectiveness of these compounds, it is usually not necessary to go above this figure. A preferred range of concentrations of fluoro substituted aromatic amines in hydrocarbon fuels is from about 2 to about grams per gallon as it is seldom necessary to go beyond these limits to obtain excellent antiknock effect. However, the most preferred embodiment of this invention comprises a liquid hydrocarbon fuel containing from about 2 grams to about 10 grams of a fluoro substituted aromatic amine per gallon.

The following examples in which all parts are parts by weight, unless otherwise stated, illustrate typical fuel compositions within the scope of this invention.

Example I To 3325 parts of benzene is added 3 parts of o-fiuoro aniline and the mixture is agitated until the o-fluoro is completely dissolved in the benzene.

Example [I One hundred and twenty-five parts of N-phenyl-p-fluoro aniline is added to 2622 parts of isooctane and the mixture is blended as in Example I.

Example III Seventy parts of p-fiuoro aniline was added with agitation to 1000 parts of a synthetic fuel consisting of 20 volume percent toluene, 20 volume percent diisobutylene, 20 volume percent isooctane and 40 volume percent nheptane. The resulting fuel showed vastly improved antiknock characteristics over the synthetic mixture which contained no p-fluoro aniline as will be pointed out in greater detail hereinafter.

Example IV Example III was repeated except that 59 parts of N- methyl-p-fiuoro aniline was added to 1000 parts of the synthetic fuel mixture to give a fuel which is far superior to the synthetic mixture to which no fluoro substituted aromatic amine had been added.

Example V Example VI Sixty parts of N-ethyl-m-fluoro aniline is added with.

stirring to 2856 parts of a gasoline havingan initial boiling point of 93 F. and a final boiling point of 378 F.,.

and which contains 35.3 volume percent parafiins, 34.2

volume percent olefins and 30.5 volume percent aromatics. This gasoline has a gravity of 562 API.

Example VII To 2924 parts of a liquid hydrocarbon fuel containing 49.9 volume percent paraffins, 15.9 volume percent olefins and 34.2 volume percent aromatics, and which has an API gravity of 1.5 an initial boiling point of 111 F. and a final boiling point of 394 F. is added 2 parts of pfluoro aniline according to the procedure of Example VI.

Example VIII Ten parts of N-methyl-p-fiuoro aniline is added to 2865 parts of a gasoline having an initial boiling point of 81 F. and a final boiling point of 410 F. This fuel contains 49.7 volume percent parafiins, 22.3 volume percent unsaturated hydrocarbons and 28.0 volume percent aromatic hydrocarbons. The gravity of this fuel is 623 API.

Example IX To 3000 parts of an aviation gasoline having a final boiling point of 338 F. and a 50 percent evaporation temperature of 221 F. is added parts of N-isopropyl-Z- ethyl-4-fluoro aniline.

Example X Example IX is repeated except that parts of N-(2'- naphthyl)-2-fluoro aniline is added to the fuel.

Example XI To 3000 parts of the fuel in Example V is added 5 parts of 2,6-dimethyl-4-iiuoro aniline.

Example XII Example VI is repeated except that 6 parts of m-fluoro aniline is added to 3000 parts of the fuel.

Example XIII Three parts of 2-iiuoro-4-methyl diphenyl amine are added with agitation to 2600 parts of the fuel described in Example VII. 1

Example XIV Nine parts of 2-fluoro-5-tert-butyl aniline is dissolved in 2900 parts of the fuel described in Example VIII.

Example XV Ten parts of N-benzyl-2-fluoro-3,6-diisopropyl-4,5'-nhexyl aniline is dissolved in 280 parts of the fuel described in Example III.

Example XVI Fifteen parts of N-(2'-methyl-5f-sec-propyl phenyl)-2,3- 5,6-tetrahexyl-4-fiuoro aniline is dissolved 300 parts of the fuel described in Example V. i

Example XVII I Sixty-five parts of N-(sec-butyl)-2-fiu0ro-3,5,6-tri-(tertmethyl butyl)aniline is added with agitation to 280 parts of the fuel of Example IX.

Example XVIII To 2900 parts of the fuel of Example VI is added 10 parts of p-fluoro aniline and the mixture is stirred until the p-fluoro aniline is completely dissolved.

Example XIX 4 Society for Testing Materials; Procedure D908-5L This procedure is referred to as the Research Method for antiknock testing. The fuel on which these tests were conducted was the synthetic fuel described in Example III. This fuel was chosen for the tests as it is representative of average present-day commercial gasoline and gives a constant performance. That is, the octane rating of this fuel will not vary between blends as will commercial gasoline depending on refinery charge stock used for the particular run. The results of these tests are summarized in Table I.

TABLE I Test No. Additive Weight Octane Percent Number 1 p-Fluoro Aniline 2.56 86.0

N-Methyl-p-fluoro Aniline.--" 2. 16 84. 2

Aniline 2. 56 80. 1

Aniline 2. 16 79- 7 N0 additive 0 77. 1

With reference to Table I it can be seen that the addition of a small quantity of a fiuoro substituted aromatic amine not only vastly improves the octane number of a fuel but does so to a much greater extent than does aniline itself. Comparing Test No. 1 to Test No. 5 indicates that the octane number was increased by about 9 when 2.56 grams of p-fiuoro aniline were added per gallon of fuel. By comparing Test No. 3 to Test No. 5 it can be seen that aniline when added in the same concentration increased the octane number by only 3. Similarly, by comparing Test No. 2 to Test No. 5 it is seen that the addition of 2.16 grams of N-methyl-p-fluoro aniline increased the octane number by over 7 while comparing Test No. 4 to Test No. 5 indicates that an identical amount of aniline increased the octane number less than 3.

Referring again to the data in Table I, it is apparent that p-fluoro aniline is about 300 percent as effective as aniline itself as an antiknock agent. Likewise, N-methylp-fluoro aniline is more than 270 percent as effective as aniline in antiknock effect. From the foregoing results it is apparent that this invention provides fuels which have vastly improved antiknock properties as compared to prior art fuel compositions.

The compounds of this invention are superior as antiknock agents because they not only possessexceptional antiknock activity but they also combine to a high degree the ancillary properties necessary for a successful commercial antiknock. Thus, for example, our compounds are superior because of their favorable solubility, volatility, and state of aggregation characteristics (e. g. boiling point). Being liquids or low melting solids or semi-solids soluble to a high degree in liquid hydrocarbons, they are easily blended with gasoline and are readily and smoothly inducted with the gasoline into the combustion chamber of the engine where they exert their antiknock efiect. Because of their good volatility characteristics they are also distributed equally among the cylinders of a multicylinder engine.

The fluoro substituted aromatic amines which may be used in the practice of this invention include ortho-, metaand para-fiuoro amine compounds which may have other ring substituents and which may be either primary or secondary aromatic or mixed aromatic aliphatic amines. Examples of these compounds include o-fluoro aniline, m-fiuoro aniline, p-fluoro aniline, 2-methyl-3- fluoro aniline, 2-fiuoro-3-methyl aniline, 2-methyl-4-fiuoro aniline, 3-methyl-4-fluoro aniline, 2-fiuoro-4-methyl aniline, 2,5-dimethyl-3-fluoro aniline, 2,5-dimethyl-4-fiuoro aniline, 2,3-dimethyl-6-fiuoro aniline, 2-fluoro-3-ethyl aniline, 2-ethyl-4-fiuoro aniline, 2-methyl-5-ethyl-4-fluoro aniline, 3-n-propyl-4-fiuoro aniline, 2-fiuoro-6-isopropyl aniline, 2-isopropyl-3-fluoro-5-ethyl aniline, 2,6-di-tertbutyl-4-fluoro aniline, 2-fiuoro-4-n-amyl aniline, 3-fluoro- S-n-decyl aniline, N-methyl-p-fluoro aniline, N-ethyl-m-- p-fluoro. aniline, -N-(l-naphthyl).-p-fluoro aniline, N-(Z- methyl-l-naphthyl)-o fluoro aniline, N-amyl-m-fluoro aniline, n-decyl-o-fluoro aniline, o-fluoro diphenyl amine, 2- fluoro-2'-methyl diphenyl amine, N-(2-methylbenzyl)-mfluoro aniline, 4-isopropyl-4'-fiuoro diphenyl amine, 2- fluoro-4-ethyl-3,5-dimethyl diphenyl amine, 2-fluoro-4- n-.decyl-3'-tert-butyl diphenyl amine, p,p-difiuoro diphenyl amine, o,p'-difluoro diphenyl amine, m,p-difiuoro diphenyl amine, N-cyclohexyl-m-fluoro aniline, 2,3,4,5- tetramethyl-6-fluoro aniline, 2-n-propyl-3-fluoro-4,5,6-trimethyl aniline, 2,3,5,6-tetra-n-hexyl-4-fiuoro aniline, N- (2'-naphthyl)-2-methyl-3-fluoro-4,6-di-n-amyl aniline, N- (2'-m-dimethyl phenyl ethyl)-2-fluoro-3,5-dimethyl-4,6- diethyl aniline and N-(3 methyl cyclopentyl)-3-fluoro- 4,5-di-n-butyl aniline.

Although compounds of the above type may all be used in the practice of this invention, because of their greater effectiveness per unit Weight, compounds in Which the N-substituent is an alkyl or hydrogen group having up to 4carbon atoms, an aryl, 'alkaryl or aralkyl group having at most 10 carbon atoms, and .in which there are from one to four ring substituents having from 1 to 6 carbon atoms each are preferred.

In the most preferred embodiment of this invention, compounds in which the fluorine atom is para to the amino group are used as it has been found that these are the most effective antiknock agents when added to liquid hydrocarbon fuels and .thus the most preferred compounds for use in the practice of this invention are para-substituted primary aromatic amines and secondary aromatic amines having other substituents as defined above. Of these compounds the most effective have been found to be para-fluoro aniline and N-methyl-p-fiuoro aniline. Para-fluoro aniline gives superior results when added to fuels of the gasoline type.

The fuels which may be used in the practice of this invention may be pure or mixed hydrocarbons or liquid hydrcarbon fuels of the gasoline boiling range. These fuels are usually blends of two or more components and can contain all types of hydrocarbons, including paraffins, both straight and branched chain, olefins, cycloalpihatics containing paraffin or olefin side chains, and aromatics containing aliphatic side chains. The fuel type depends on base stock from which it is obtained and on the method of refining. For example, it can. be a straight run or processed hydrocarbon, including thermally cracked, catalytically cracked, reformed, hydroformed, etc. The boiling range of the components of the gasoline can vary from to about 430 F., although the boiling range of the fuel blend is often found to be between an initial boiling point of from about 80 F. to 100 F. and a final boiling point of about 430 F. While the above is true for ordinary gasoline, the boiling range is a little more restricted in the case of aviation gasoline. Specifications for the latter often require that the boiling range be from about 82 F. to about 338 F., with certain fractions of the fuel boiling away at a particular intermediate temperature.

The fuels of this invention may contain from 0.3 gram to 250 grams of a fluoro substituted aromatic amine depending upon the particular fuel, the fluoro substituted amine compound used, and the end result desired. Thus, if a fuel having an initial octane rating of about 40 is to be made suitable for use in a standard automobile engine it may be necessary to add as much as 250 grams per gallon of fluoro substituted aromatic amine having a relatively high (250) molecular weight. However, a fuel having an initial octane number of about 80 can be made suitable for most purposes by the addition of from 2 to 10 grams per gallon of a fluoro substituted aromatic amine such as N-methyl-p-fiuoro aniline having relatively low molecular weight.

The fluoro substituted aromatic amines suitable for use in preparing the fuels 'of this invention may-be prepared; by any convenient method known in the literature. Some,

aniline may be prepared from p-fluoro aniline by first preparing N-(p-fluoro phenyl)-p-toluene sulfonamide and reacting this compound with methyl iodide, followed by hydrolysis to the desired N-methyl-p-fiuoro aniline.

Ortho-fiuoro aniline has been prepared by the reduction of Z-fiuoro-l-nitrobenzene with iron powder and dilute sulfuric acid While meta-fluoro aniline may be prepared by heating the meta-isomer of with hydrofluoric acid. Other methods of preparing these compounds will readily suggest themselves to one skilled in the art.

The fuels of this invention may contain, in addition to fluoro substituted aromatic amines, other compounds which are normally added to liquid hydrocarbon fuels to improve the properties thereof. Thus, antioxidants, dyes,v

corrosion inhibitors, other antiknock agents and scavengers when necessary for these antiknock agents are beneficially added to the fuels of this invention. In particular, small quantities of metal carbonyl compounds, for example, iron carbonyl, nickel carbonyl, manganese cars bonyl or other metal carbonyls may be used in conjunction with the fluoro substituted aromatic amine-containing fuels of this invention. Likewise, it is desirable to include such metal organic compounds as cyclopentadie'nyl iron,

other cyclopentadienyl metal compounds or derivatives of these compounds with the fuels of this invention.

Specifically, it is desirable to include with the fuels of this invention an o-rganolead antiknock agent such as tetraethyllead and an appropriate scavenger therefor. Fluoro substituted amine compounds when included in leaded fuels can be used in approximately the same proportions as set forth in detail hereinbefore. Thus, from about 0.3 to about 250 grams per gallon of fuel of a fluoro substituted aromatic amine compound may advantageously be included in fuels having up to 6 milliliters of tetraethyllead per gallon. However, it is preferred to include from about 2 to about 10 grams of a fluoro substituted aromatic amine in these leaded fuels. The following examples are illustrative of the use of organolead antiknock in conjunction with the fluoro substituted aromatic amine-containing fuels of this invention.

Example XX To gallons of the fuel described in Example III is added 165.9 grams of tetraethyllead, 50.76 grams of ethylene dichloride, 48.18 grams of ethylene dibromide and 25,000 grams of N-(l-naphthyl)-2,3,5,6-tetra-n-amylp-fluoro aniline.

Example XXI 331.8 grams of tetraethyllead, 101.42 grams of ethylene dichloride, 96.36 grams of ethylene dibromide and 1000 grams of N-methyl-p-fluoro aniline are added to 100 gallons of the fuel described in Example V.

Example XXII To 100 gallons of the fuel described in Example VI is added 497.7 grams of tetraethyllead, 152.18 grams of ethylene dichloride, 144.54 grams of ethylene dibromide and 200 grams of p-fiuoro aniline.

Example XXIII Example XXII is repeated except that 500 grams of N-phenyl-m-fiuoro aniline are added to the fuel in lieu of p-fiuoro aniline.

Example XXIV To 100 gallons of the fuel described in Example IX is added 1000 grams of 3,5-diethyl-4-fluoro aniline, 663.6

mangoes 7 grams of tetraethyllead and 385. 44- grams of ethylene dibroinidei Example XXV Example XXIV is repeated except that 30 grams of where R is a member of the group consisting of hydrogen, alkyl, aryl, aralkyl, alkaryl and cycloalkyl; R is alkyl and n is an integer from 0 to 4; said compound being present in an amount sufficient to improve the antiknockproperties of said fuel.

2. The composition of claim 1 wherein the concentration of the fluoro substituted aromatic amine compound is from about 0.3 grams toabout 250 grams per gallon of fuel.

3; The composition of claim 1 wherein the concentration of the fiuoro substituted aromatic amine com- 8 pound is from about 2 to" about gr'a'ms per gallon: oi fuel.

4; The" composition of claim" 1 wherein the fiuordstib stituted aromatic amineis p-fiuo'ro aniline.

5. The compositiono'f claim 1 wherein thefluor'osub' stituted aromatic amine is N methyl-p-fiuoro' aniline.

6. A hydrocarbon fuel of the gasoline boiling range for use in spark ignition internal combustion engines containing from about 2 to about 10 grams per gallon of p-fluoro aniline.

7. A hydrocarbon fuel ofthe gasoline boiling rangefor use in spark ignition internal combustion engines containing from about 2 to about 10 grams per gallon of N-methyl-p-fiuoro aniline.

References Cited in the file of this patent UNITED STATES PATENTS Howell et al Nov. 18, 1952 OTHER REFERENCES 

1. A HYDROCARBON FUEL OF THE GASOLINE BOILING RANGE FOR USE IN SPARK IGNITION INTERNAL COMBUSTION ENGINES CONTAINING A SMALL AMOUNT OF A FLUORO SUBSTITUTED AROMATIC AMINE COMPOUND HAVING THE FORMULA 